Cooling means for hot blast stoves



Aug. 28, 1962 WALTHER 3,051,463

COOLING MEANS FOR HOT BLAST STOVES Filed March 3, 1961 FIGJ mmk ATTORNEY Patented Aug. 28, 1962 fire Germany, a corporation of Germany Filed Mar. 3, 1961, Set. No. 93,144 8 Claims. (Cl. 263-19) The present invention relates to improvements in hot blast stoves of the type that are used to provide a stream of hot blast to a blast furnace.

A hot blast stove of this type usualy operates cyclically between two other different conditions thereof, namely, an On Gas and an On Blast condition. During the On Gas condition, the stove is being heated by means of a gas-air mixture which is consumed in the combustion chamber of the stove causing resultant hot flue gases to heat up the checker work of the stove before exiting through a chimney. During the On Blast condition, cold air is forced through the stove, thereby passing through the checker work which has been previously heated during the On Gas condition. This cold air is thus being heated by the checker work and leaves the stove as hot air or hot blast ready to go into the blast furnace where it is required.

For a hot blast stove to be enabled to assume the On Gas condition, it is usually equipped with a burner which has a flame for igniting the gas-air mixture, 8. burner shut-off valve which functions to isolate the burner from the hot blast stove, and a chimney valve through which the flue gases exhaust after heating the checker work. For the stove to assume the On Blast condition, it is usually provided with a cold blast valve through which cold air is admitted into the stove, and with a hot blast valve through which the heated air blast leaves the stove prior to its being introduced into the furnace. When a hot blast stove is On Gas, its burner shut-off valve is open, while its cold blast valve and hot blast valve are closed. n the other hand, when the stove is On Blast, the burner shut-off valve is closed, while the cold blast valve and hot blast valve are open. In constructing stoves of this type, it is common to have the burner shut-off valve in relatively close proximity to the hot blast stove. This common occurrence is due to good design practice dictated by the usual locations of the hot blast main, gas and air mains. There is, however, a problem which arises from such an arrangement. More specificaly, the temperature at the hot blast valve when a stove is On Blast is often in the area of 1000" C. The heat at the hot blast valve is therefore transmitted to the burner shut-off valve when the latter is in close proximity thereto. This resulting temperature rise at the burner shut-off valve is highly undesirable, for obvious reasons, and it therefore becomes necessary to provide means for cooling the burner shut-off valve, and particularly the valve plate thereof. Conventional cooling means for performing this function are well known, such as water cooling in the usual way. These conventional cooling means, however, have proved to be costly and relatively cumbersome.

It is therefore an object of the present invention to provide new and improved means for cooling the burner shut-off valve of a hot blast stove.

Another object is the provision in a hot blast stove of means for air-cooling the burner shut-off valve, utilizing air from the cold blast main for the stove.

Another object is the provision of means for cooling the burner shut-off valve by automatically introducing cold blast into said valve only when the stove is in the On Blast condition.

The above and other objects, features and advantages of the present invention will be more fully understood from the following description considered in connection with the accompanying illustrative drawings.

In the drawings:

FIG. 1 is a schematic representation of a hot blast stove showing the stove and some of its valves and conduits leading thereto, illustrating the invention;

FIG. 2 is a schematic representation as seen by viewing FIG. 1 along the direction of arrow 2; and

FIG. 3 is a fragmentary view partly in section, and on a larger scale, showing the details of the burner shutoff valve and the passage of the cooling air therethrough and into the stove, seen from the direction of arrow 3 in FIG. 2.

Referring now to the drawings, and particularly to FIG. 1 and 2, reference numeral 10 indicates a hot blast stove of the type which is used for providing hot blast to a blast furnace. When such stove 10 is On Gas, air is introduced through conduit 12, gas through conduit 14, and the mixture passes through the burner shut-off valve 16 into stove 10'. The combustion of this gas-air mixture produces very hot flue gases which pass through checker work 18 of the stove, heating the latter, and then these flue gases escape through a chimney valve, schematically shown at 20. The solid arrows in FIG. 2 indicate the path of the air-gas mixture and flue gases when the stove is On Gas.

When stove 10 is On Blast, cold blast from the cold blast main 22 passes through cold blast valve 24 into, stove 10, as at 25, where it is heated by the checker work 18 and then leaves the stove through hot blast valve 26 into hot blast main 2%, on its way to the blast furnace. The dot-and-dash arrows in FIG. 1 indicate the path of the air blast when stove 10 is On Blast.

It will be understood, of course, that when stove 10 is On Gas, burner shut-off valve 16 and chimney valve 26 are open, while cold blast valve 24 and hot blast valve 26 are closed, and when stove 10 is On Blast, cold blast valve 24 and hot blast valve 26 are open, while burner shut-off valve 16 and chimney valve 20 are closed. As can be seen from FIG. 1 and FIG. 2, burner shutoff valve 16 is in very close proximity to hot blast valve 26. Accordingly, the heat from the hot blast valve 26, caused by the fact that the hot blast temperature at that point is approximately 1000 C., is easily transmitted to the burner shut-off valve 16.

The resulting heat rise in the burner shut-off valve 16 must be dissipated and for that reason it becomes necessary to cool the burner shut-off valve while the stove is in the On Blast condition. Toward that end, there is provided a conduit 30 through which some of the cold air passing through cold blast valve 24 is bypassed and introduced into the burner shut-off valve 16, as best seen in FIGS. 1 and 2.

Referring to FIG. 3, there is shown on an enlarged scale the gas shut-off valve 16 into which the cold air is introduced. Gas shut-off valve 16 comprises an upper housing 32 which houses a link 34, operated by an electrical drive unit 36. Linkage 34 is operatively connected to valve plate 38 for raising and lowering the same in opening and closing, respectively, the gas shut-off valve. As shown in FIG. 3, the valve plate 38 is in the closing position thereof. Bypass conduit 36 terminates in a nozzle type part 46* which passes through an opening in upper housing 32. As shown in FIG. 3, all the cold air bypassed through conduit 30 enters upper housing 32 and passes through the stove side of valve plate 38, cooling the same. Thereafter, this cooling air enters the stove proper 10, cooling burner head 39 of stove 10, the path of the cooling air being indicated by the dashed arrows. It will be noted that the supply of air passing through conduit 30 for cooling valve 16, originates from the cold blast main 22. More specifically, this supply of air comes from cold blast main 22 and passes through cold blast valve 24 before being bypassed in conduit 30. In this way, cold air is fed to the burner shut-off valve only when cold blast valve 24 is open. This condition occurs only when the stove is On Blast, and that is the only time when it is desired to have the burner shut-off valve cooled in the manner indicated above. When stove 10 is in the On Gas condition, cold blast valve 24 is necessarily closed and burner shut-oif valve 16 is open to permit the air and gas mixture coming from conduits 12 and 14 to pass therethrough on the way to the stove where such mixture is consumed. Thus it is seen that providing cooling air as described above can occur only at a time when stove 10 is On Blast. This is a safety precaution which is absolutely necessary, and which is obtained automatically in the arrangement in accordance with the invention. In actual practice, the respective valves of a stove are interlocked so that the valves of a stove are operated in a predetermined sequence whereby the cold blast valve of the stove is opened only after the burner shut-off valve has been closed. An apparatus for interlocking the valves of a stove in this manner is fully disclosed in Patent No. 2,931,635, issued April 5, 1960, and assigned to the assignee hereof. As a further safety device, bypass conduit 30 may be provided with a one-Way valve 42 to prevent any back flow of gas, when the stove is On Gas, from the burner through conduit 30 into the stove, underneath the checkerwork, and out through the chimney valve into the stack. The cooling air which is forced into burner shut-E valve 16 through conduit 30 while the stove is On Blast, enters stove 10. This cooling air is heated by the hot checker work 18 and then exits through the hot blast valve 26, in the same way as the bulk of cold air which is introduced into the stove through cold blast valve 24 at 25.

The amount of cold blast going into a stove through point 25 is determined by the heat requirements of such stove. What is of great import in the cooling means for the burner shut-off valve, according to the invention, is the fact that the amount of cold air bypassed through conduit 30 is a function of the amount of cold blast fed into the stove. In this way, it will be seen that the cooling systern is a self-regulating one. More specifically, if more cold blast is introduced into the stove for purposes of being heated and becoming hot blast, then similarly more cold air will be bypassed in conduit 30 for cooling the burner shut-off valve 16 and more particularly, for cooling valve plate '38 and upper housing 32 thereof, as well as burner head 39. The cooling system, therefore, is seen to be automatically self-regulating and also automatically placed in operation when the need for cooling arises. In other words, as soon as stove goes into the On Blast condition, cold air is available in proportion to the heat requirements of the stove, for cooling the burner shut-0E valve.

Itis therefore seen that the cooling means in accordance with the invention is extremely simple and economical in-construction in that it utilizes as the cooling medium the same air which is made available from the cold blast main during the normal operation of the stove. Furthermore, the cold blast valve which is part of the stove system now serves the additional function of controlling the cold air to be furnished as the cooling medium for the hot blast valve. The resulting simplicity and economy of this construction, together with the automatic regulating and safety features thereof render the system immensely valuable for performing its intended function.

While I have shown and described the preferred embodiment of my invention, it will be understood that the invention may be embodied otherwise than as herein specifically illustrated or described, and that in the illustrated embodiment certain changes in the details of construction and in the form and arrangement of parts may be made without departing from the underlying idea or principles of this invention within the scope of the appended claims.

Having thus described my invention, what I claim and desire to secure by Letters Patent, is:

1. In a hot blast stove adapted to supply hot blast to a blast furnace and being periodically changed between an On Gas condition thereof in which the stove checker work is heated by the combustion of an air-gas mixture and an On Blast condition thereof in which cold air is introduced into the stove, passes by the checker work to be heated thereby, and exits from the stove as hot blast destined for the blast furnace, said stove having a cold blast valve through which said cold air originating from a cold blast main passes before entering the stove and a hot blast valve through which the air heated by the checker work exits the stove when :the stove is in the On Blast condition, said stove also having a burner shut-off valve through which an air-gas mixture enters the stove, when the latter is in the On Gas condition, where combustion thereof takes place for heating said checker work; the improvement comprising means for cooling the burner shutoff valve, said cooling means comprising conduit means having an inlet adapted to be in fluid communication with said cold blast main through which cooling air from the cold blast main is introduced and having an outlet connected to said burner shut-off valve through which said cooling air is introduced into the burner shut-off valve for cooling the latter, and means for preventing said cooling air from being introduced into said burner shut-off valve at any time that the latter is open and has an air-gas mixture passing therethrough.

2. In a hot blast stove adapted to supply hot blast to a blast furnace and being periodically changed between an On Gas" condition thereof in which the stove checker work is heated by the combustion of an air-gas mixture and an On Blast condition thereof in which cold air is introduced into the stove, passes by the checker work to be heated thereby, and exits from the stove as hot blast destined for the blast furnace, said stove having a cold blast valve through which said cold air originating from a cold blast main passes before entering the stove and a hot blast valve through which the air heated by the checker work exits the stove when the stove -is in the On Blast condition, said stove also having a burner shut-0E valve through which an air-gas mixture enters the stove, when the latter is in the On Gas condition, where combustion thereof takes place for heating said checker work; the improvement comprising means for cooling the burner shut-off valve, said cooling means comprising conduit means having an inlet adapted to be in fiuidcommunication with said cold blast main through which cooling air from the cold blast main is introduced and having an outlet connected to said burner shut-01f valve through which said cooling air is introduced into the burner shut-off valve for cooling the latter, said conduit means inlet being disposed between the cold blast valve and the stove whereby said cooling air is introduced into said burner shut-off valve only when said cold blast valve is open.

3. In a hot blast stove adapted to supply hot blast to a blast furnace and being periodically changed between an On Gas condition thereof in which the stove checker work is heated by the combustion of an air-gas mixture and an On Blast condition thereof in which cold air is introduced into the stove, passes by the checker Work to be heated thereby, and exits from the stove as hot blast destined for the blast furnace, said stove having a cold blast valve through which said cold air originating from a cold blast main passes before entering the stove and a hot blast valve through which the air heated by the checker work exits the stove when the stove is in the On Blast condition, said Steve also having a burner shut-0E valve through which an air-gas mixture enters the stove, when the latter is in the On Gas condition, Where combustion thereof takes place for heating said checker work; the improvement comprising means for cooling the burner shut-off valve, said cooling means comprising conduit means having an inlet adapted to be in fluid communication with said cold blast main through which cooling air from the cold blast main is introduced and having an outlet connected to said burner shut-off valve through which said cooling air is introduced into the burner shut-off valve for cooling the latter, and means in said conduit means to prevent any flow therein in the direction of said inlet, and means for preventing said cooling air from being introduced into said burner shut-01f valve at any time that the latter is open and has an air-gas mixture passing therethrough.

4. In a hot blast stove adapted to supply hot blast to a blast furnace and being periodically changed between an On Gas condition thereof in which the stove checker work is heated by the combustion of an air-gas mixture and an On Blast condition thereof in which cold air is introduced into the stove, passes by the checker work to be heated thereby, and exits from the stove as hot blast destined for the blast furnace, said stove having a cold blast valve through which said cold air originating from a cold blast main passes before entering the stove and a hot blast valve through which the air heated by the checker work exits the stove when the stove is in the On Blast condition, said stove also having a burner shut-off valve through which an air-gas mixture enters the stove, when the latter is in the On Gas condition, where combustion thereof takes place for heating said checker work; the improvement comprising means for cooling the burner shutoff valve, said cooling means comprising conduit means having an inlet adapted to be in fluid communication with said cold blast main through which cooling air from the cold blast main is introduced and having an outlet connected to said burner shut-off valve through which said cooling air is introduced into the burner shut-01f valve for cooling the latter, said conduit means inlet being disposed between the cold blast valve and the stove whereby said cooling air is introduced into said burner shutoif valve only when said cold blast valve is open, and means in said conduit means to prevent any flow therein in the direction of said inlet.

5. In a hot blast stove adapted to supply hot blast to a blast furnace and being periodically changed between an On Gas condition thereof in which the stove checker work is heated by the combustion of an air-gas mixture and an On Blast condition thereof in which cold air is introduced into the stove, passes by the checker work to be heated thereby, and exits from the stove as hot blast destined for the blast furnace, said st ove having a burner head, said stove having a cold blast valve through which said cold :air originating from a cold blast main passes before entering the stove and a hot blast valve through which the air heated by the checker work exits the stove when the stove is in the On Blast condition, said stove also having a burner shut-off valve through which an air-gas mixture enters the stove, when the latter is in the On Gas condition, where combustion thereof takes place for heating said checker work, said burner shutoff valve having a valve plate, said cold blast valve and hot blast valve being open and said burner shut-off valve being closed when the stove is On Blast, said cold blast valve and hot blast valve being closed and said burner shut-off valve being open when the stove is On Gas; the improvement comprising means for cooling the burner shut-ofi valve, said cooling means comprising conduit means having an inlet adapted to be in fluid communication with said cold blast main through which cooling air from the cold blast main is introduced and having an outlet connected to said burner shut-off valve through which said cooling air is introduced into the burner shut-off valve for cooling the latter, and means for directing said introduced cooling air past the stove side of the burner shut-off valve plate, past the burner head, and into the stove where said introduced air is heated by the checker work and exits as hot blast through the hot blast valve, and means for preventing said cooling air from being introduced into said burner shutv t 6 01f valve at any time that the latter is open and has an airgas mixture passing therethrough.

6. In a hot blast stove adapted to supply hot blast to a blast furnace and being periodically changed between an On Gas condition thereof in which the stove checker work is heated by the combustion of an air-gas mixture and an On Blast condition thereof in which cold air is introduced into the stove, passes by the checker work to be heated thereby, and exits from the stove as hot blast destined for the blast furnace, said stove having a burner head, said stove having a cold blast valve through which said cold air originating from a cold blast main passes before entering the stove and a hot blast valve through which the air heated by the checker work exits the stove when the stove is in the On Blas condition, said stove also having a burner shut-0E valve through which an airgas mixture enters the stove, when the latter is in the On Gas condition, where combustion thereof takes place for heating said checker work, said burner shut-off valve having a valve plate, said cold blast valve and hot blast valve being open and said burner shut-off valve being closed when the the stove is On Blast, said cold blast valve and hot blast valve being closed and said burner shut-oil? valve being open when the stove is On Gas; the improvement comprising means for cooling the burner shut-ofl? valve, said cooling means comprising conduit means having an inlet adapted to be in fluid communication with said cold blast main through which cooling air from the cold blast main is introduced and having an outlet connected to said burner shut-off valve through which said cooling air is introduced into the burner shut-off valve for cooling the latter, and means for directing said introduced cooling air past the stove side of the burner shut-off valve plate, past the burner head, and into the stove where said introduced air is heated by the checker work and exits as hot blast through the hot blast valve, said conduit means inlet being disposed between the cold blast valve and the stove whereby said cooling air is introduced into said burner shutoff valve only when said cold blast valve is open, when the stove is in the On Blast condition.

7. In a hot blast stove adapted to supply hot blast to a blast furnace and being periodically changed between an On Gas condition thereof in which the stove checker work is heated by the combustion of an air-gas mixture and an On Blast condition thereof in which cold air is introduced into the stove, passes by the checker Work to be heated thereby, and exits from the stove as hot blast destined for the blast furnace, said stove having a cold blast valve through which said cold air originating from a cold blast main passes before entering the stove and a hot blast valve through which the air heated by the checker Work exits the stove when the stove is in the On Blast condition, said stove also having a burner shut-off valve through which an air-gas mixture enters the stove, when the latter is in the On Gas condition, where combustion thereof takes place for heating said checker work, said burner shut-off valve having a valve plate, said cold blast valve and hot blast valve being open and said burner shut-cit being closed when the stove is On Blast, said cold blast valve and hot blast valve being closed and said burner shut-oif valve being open when the stove is On Gas; the improvement comprising means for cooling the burner shut-off valve, said cooling means comprising conduit means having an inlet adapted to be in fluid communication with said cold blast main through which cooling air from the cold blast main is introduced and having an outlet connected to said burner shut-off valve through which said cooling air is introduced into the burner shutoif valve for cooling the latter, and means for directing said introduced cooling air past the stove side of the burner shut-0E valve plate and into the stove where said introduced air is heated by the checker work and exits as hot blast through the hot blast valve, and means in said conduit means to prevent any flow therein in the direction of said inlet.

8. In a hot blast stove adapted to supply hot blast to a blast furnace and being periodically changed between an On Gas condition thereof in which the stove checker work is heated by the combustion of an air-gas mixture and an On Blast condition thereof in which cold air is introduced into the stove, passes by the checker work to be heated thereby, and exits from the stove as hot blast destined for the blast furnace, said stove having a cold blast valve through which said cold air originating from a cold blast main passes before entering the stove and a hot blast valve through which the air heated by the checker work exits the stove when the stove is in the On Blast condition, said stove also having a burner shutoff valve through which an air-gas mixture enters the stove, when the latter is in the On Gas condition, where combustion thereof takes place for heating said checker work, said burner shut-off valve having a valve plate, said cold blast valve and hot blast valve :being open and said burner shut-off valve being closed when the stove is On Blast, said cold blast valve and hot blast valve being 20 closed and said burner shut-ofi valve being open When the stove is On Gas; the improvement comprising means for cooling the burner shut-elf valve, said cooling means comprising conduit means having an inlet adapted to be in fluid communication with said cold blast main through which cooling air from the cold blast main is introduced and having an outlet connected to said burner shut-0E valve through which said cooling air is introduced into the burner shut-off valve for cooling the latter, and means for directing said introduced cooling air past the stove side of the burner shut-olt valve plate and into the stove where said introduced air is heated by the checker work and exits as hot blast through the hot blast valve, said conduit means inlet being disposed between the cold blast valve and the stove whereby said cooling air is introduced into said burner shut-off valve only when said cold blast valve is open, when the stove is in the On Blast condition, and means in said conduit means to prevent any flow therein in the direction of said inlet.

Beardsley July 1, 1930 Hel-lan July 28, 1936 

